GETTING STARTED USING LINKWINDS
DATA LINKING
The key to using LinkWinds is data linking. It provides the user the
ability to interactively link the many applications of LinkWinds for
concerted actions in examining data. It is especially effective in
detecting trends, anomalies and correlations.
Data linking is affected through two icons. The link icon is a button
displaying two interlocked rings, while the unlink icon displays two
rings that are separated. LinkWinds' objects may have a single link
button, in the case of the DataObject; the full set of link and unlink
buttons, the case for all controls such as the slider; or no buttons, in
the case of a display object. To perform a link, the left-mouse button
is pressed while the cursor is placed on the appropriate button, and a
"rubber band" is dragged out and dropped into the application to be
linked. To break the link, the same thing is done using the unlink
button. The rubber bands indicating the current links may be displayed
at any time during a session by placing the cursor in the logo of the
top-level menu and pressing the left-mouse button. They are shown
emanating from the source button to the center of the destination
object.
There are two simple rules to follow in applying the linking paradigm:
1. When, as a result of a top-level menu selection of a control or
display, an empty window appears on the screen, put data into it. This
is done by linking a DataObject into the window.
2. When an object with the pair of link symbols appears, exercise its
control function by linking it into the object to be controlled. Once
the link is made, the message flow to the object is enabled. For
instance, in the case of links from a slider, each time the slider is
moved, its final value is broadcast to all objects to which it is
linked. When the "track" toggle is pressed, a continuous stream of
messages results as the slider is moved.
All LinkWinds controls are operated with the left-mouse button and all
menus with the right-mouse button.
A SAMPLE SESSION
To help you get started using LinkWinds, a sample session is presented
below. We show the steps to be taken to look one of the sample
databases, and explain what is accomplished by the steps.
1. In your own LinkWinds directory, execute LinkWinds by typing lw.
The LinkWinds top-level menu will appear under the cursor. Place it
where you wish and press the left-mouse to fix it there.
2. Open the "Databases" menu button and under the "Ocean" entry, select
the "oceanAtlas" item from the cascaded menu. This process will result
in the activation of the next, or "Data" menu button.
3. Open the "Data" menu and you will see the files associated with the
selected database. In this case, there are three: "Oxygen Content",
"Temperature" and "Salinity". Select "Oxygen Content" and a DataObject
representing that data set will appear at the cursor to be placed where
desired. Then, in like manner, bring up the "Temperature" data set.
4. Open the "Tools" menu button and bring "Image" to the screen.
You'll observe an empty window.
5. Link the "Oxygen Content" DataObject to the Image window. The data
and metadata will become accessible to Image and the data will be
rendered.
6. Open the "Tools" menu again and bring a second Image to the screen.
7. Link the "Temperature data" into this Image.
8. Bring up a Slider from the "Tools" menu and link it to each of the
Image objects. By moving the slider you can then explore the two data
sets simultaneously at the various ocean depths. If you press the
"Track" button, the changes in depth will occur continuously as the
slider is moved.
9. Bring up the 2D ScatterPlot. Link to it the "Oxygen Content"
DataObject, and the "Temperature" DataObject, in that order. It will
display the two datasets scattered against one another. At a depth of 0
(on the Slider) you can observe a very high degree of anticorrelation:
as we expect, the higher the water temperature, the less oxygen will be
dissolved in it.
10. Link the Slider to the 2D ScatterPlot and you can look at the data
correlations as a function of ocean depth.
11. Move the slider to a depth of 100 meters. At this depth, you can
observe a region of low oxygen off the west coast of Central America.
12. Select "Resize Bound Box" from the "Bound Box" cascade menu in
Image1. The cursor, when placed over the oxygen content image, will
display an upper left-hand corner symbol. Place this somewhere in the
upper left vicinity of the low oxygen region and press the left mouse
button. While holding it down, drag a bounding box to the lower right
vicinity of that region. Release the mouse button and you've defined a
bounding box.
13. Link Image1 into the 2D ScatterPlot. You will see that now the
only data scattered is that lying within the bounding box. You can
redraw the box at will, or by selecting the menu item, "Move Bound Box"
from the "Bound Box" cascade menu, you can move an existing box around
the image to look at correlations in other regions. Statistical
information about the correlations is displayed in a text window at the
bottom of the 2D ScatterPlot.
This completes your sample session which demonstrates many of the
LinkWinds operations, and its approach to data display and exploration.
Other links may be tried at will. Linking is designed to be learned
through trial and error. If an application doesn't understand the
message received through a link, it will ignore it.
For details in the use of each application, help windows can be brought
up by pressing the button contain "?". At top level help menu is
available under the LinkWinds' "System" menu item.
You have just gone through the steps that we used to create the sample
macro "Startup", which you can find under the "macros" menu button. If
you want to exercise this macro, open the "macros" menu button, and
under the "Run Macro" item select "Startup". All of the steps you have
just taken will be repeated automatically. The steps for creating a
macro are given in Section 12.
Another way to execute this sequence of steps is to start LinkWinds with
the -r switch and the .lynx filename.
lw -r startup.lynx
This demonstrates the LinkWinds rerun mode which can be used to setup an
initial environment. For further instructions, see the LinkWinds User's
Guide and Reference Manual.